Fluid exchange system for controlled and localized irrigation and aspiration

ABSTRACT

The control of fluid introduction into and out of body conduits such as vessels, is of great concern in medicine. As the development of more particular treatments to vessels and organs continues it is apparent that controlled introduction and removal of fluids is necessary. Fluid delivery and removal from such sites, usually referred to as irrigation and aspiration, using fluid exchange devices that control also need to be considerate of potential volume and/or pressure in the vessel or organ are described together with catheter and lumen configurations to achieve the fluid exchange. The devices include several electrically or mechanically controlled embodiments and produce both controlled and localized flow with defined volume exchange ratios for fluid management. The applications in medicine include diagnostic, therapeutic, imaging, and uses for the introduction or removal of concentrations of emboli within body cavities.

CROSS-REFERENCE TO OTHER APPLICATIONS

[0001] This application is a continuation-in-part of, claims the benefitof, U.S. Provisional Patent Application Serial No. 60/306,315, filedJul. 17, 2001.

FIELD OF THE INVENTION

[0002] The devices and related methods of the invention relate to thecontrolled introduction and removal of fluids in diagnostic, therapeuticand imaging applications within the body. Specifically, the inventionrelates to the advantageous use of a fluid exchange device incombination with a catheter to produce a system for controlledaspiration and irrigation and the selective and localized exchange offluids within a body conduit, for example, in the diseased region of ablood vessel having a blockage or lesion. The devices of the invention,and the methods enabled by the use of the devices, have severaldifferent components that can be used individually or integrated into asystem for use within an organ and within the vasculature of the bodywhere controlled and localized irrigation and aspiration are performedtogether as a therapeutic procedure or in tandem with a separatetherapeutic procedure.

BACKGROUND OF THE INVENTION

[0003] Irrigation and aspiration are clinically important in manysurgical procedures when fluids are selectively introduced into andremoved from a target site within the body, usually while a surgery orother therapeutic medical procedure is performed. When the site of thetherapeutic treatment is inside a body cavity or in the vasculature ofthe body, such as in a blood vessel, the irrigation and aspirationfunctions require special apparatus and methods. Surgical andpercutaneous systems that both irrigate and aspirate have beendeveloped, and some of these systems are catheter-based such that theintroduction and removal of fluids is performed within an organ or avessel by using the catheter as the conduit to introduce and removefluids from a target site. As will be readily appreciated, the catheterallows the control elements to be remotely located, e.g., outside thebody while the actual irrigation and aspiration functions areselectively provided within the body by selectively orienting the distalend of the catheter to the target site. In such cases, as is the case inopen surgeries, the irrigation and aspiration functions accompany atherapeutic procedure that is performed at the target site along withthe irrigation and aspiration.

[0004] Catheter-based irrigation and aspiration systems are unique inmany respects due to their use in clinical situations where blockages orlesions exist inside a blood vessel, such as a coronary or carotidartery, and dangers arise from the creation and release of emboli withinthe vessel. In many intravessel therapeutic procedures, the danger fromthe creation of emboli is an unavoidable aspect of the therapeuticprocedure. For example, lesions of atherosclerotic plaques inside ablood vessel are treated by several therapeutic procedures includingendarterectomy, atherectomy, the placement of intravessel stents,balloon angioplasty, surgical ablation of the lesion, thrombectomy, OCT,dialysis shunt clearing and others. However, while each of theseprocedures has great therapeutic value in treating the lesion, eachcarries the risk of creating emboli during the procedure. As with anyprocedure conducted in the cardiovascular system, the risk isparticularly great where plaque dislodged from inside a blood vessel cantravel to the brain causing serious brain injury or death. For example,treating lesions of the carotids necessarily involve high risk.Currently, carotid treatments are attempted together with deployment ofa filter to attempt to track emboli generated by or released from acarotid lesion. Unfortunately, crossing a carotid lesion with a filteror other structure can generate a cerebral ischemia or stroke. Schlueteret al. 2001, Circulation 104 (17) II-368. Moreover, studies have shownthat merely crossing a carotid lesion with a guide wire can generateemboli. Al-Mubarak et al.: Circulation 2001 OCT 23:104 (17): 1999-2002.Also, some lesions carry such a high risk of generating emboli thattherapeutic treatments are attempted only in the most severe cases.Where a chronic total occlusion exists, the diagnosis is particularlypoor because it is impossible to place a structure distal of theocclusion such that emboli generated by the removal of the occlusion canbe captured before circulating in the bloodstream. Such occlusions canonly be treated by removing the occlusion from the proximal side, whereemboli removal is uniquely difficult. Accordingly, if the capabilityexisted to dramatically reduce the dangers of emboli creation duringtherapeutic procedures inside a vessel or organ of the body, theexisting procedures would be safer and more widely practiced, and newprocedures would be performed.

[0005] A variety of systems to contain and remove emboli have beenproposed wherein a portion of a vessel that contains a lesion issegregated by two occluding members, typically two balloons, which areinflated proximate and distal to the lesion to effectively seal theinside of a region of the vessel containing a lesion prior to treatmentof the lesion. Once treatment is complete, embolic particles such asdislodged plaque are removed by applying suction between the balloons.However, the tissue affected by a lesion is notoriously delicate and thetreatment of the lesion has the capability to generate or release emboliwhenever any mechanical manipulation of the lesion occurs. Thegeneration and/or release of emboli is a concern virtually anytime astructure is passed through a susceptible vessel. Such circumstancesinclude the placement of a balloon or stent, the placement of a filter,or simply the use of a catheter or guide wire for imaging, diagnostic,or any other procedure. In many procedures, the internal portion of avessel is occluded to provide a segregated region of a vessel throughwhich fluid does not flow. Moreover, virtually anytime structures areinserted into the vessel, the generation of release of emboli is aconcern. For example, in the common practice of placing a stent insidean artery, a filter may be placed distally of the stent to attempt tocollect emboli generated when the stent is expanded to engage plaques orlesions inside the vessel. All devices placed distal involve thecrossing of the lesion. All crossings of lesions create emboli of somequantity and significance. Such systems cannot protect the patientagainst the potential harm inherent in the placing the device.Additionally, once the stent is in place, the filter must be removed bypulling it through the portion of the vessel in which the stent has beeninserted. This carries the risk that the filter will impact the vesseland cause the release of emboli and/or contact the stent and eitherdisplace the stent or similarly cause the release of embolic particles.The use of occluding members of any type has certain drawbacks. Anytimea structure is used as an occlusive member inside a vessel, thestructure must deform the vessel from the inside to create a seal aboutthe periphery thereof with the internal surface of the vessel. Forexample, to make the seal tight enough to prevent the passage of fluidand emboli past the balloon, the expansion of the balloon typicallydeforms the vessel outward and may disrupt plaque in and about the pointof contact between the vessel and the balloon. Moreover, any plaque thatbecomes dislodged outside the barrier formed by the balloon is releasedinto the blood stream because there is no mechanism distal of theballoon to remove the emboli. For this reason, irrigation and aspirationproximate to the lesion are particularly important.

[0006] To create a segregated region of a vessel, a two-balloon systemmay be used. However, certain disadvantages of a two-balloon system alsoarise from the placement of balloons on both sides of a lesion and thenature of the blood flow that occurs in the region of the vesselcontaining the lesion once the balloon is removed. At the point ofcontact between the balloon and the vessel, plaque may be compressedunderneath the balloon and may become dislodged upon reestablishment offlow through the vessel. Furthermore, many clinicians have observed thatthe region distal of a lesion is more likely to exhibit plaque formationthan the region proximal of a lesion. Thus, the use of an occludingmember distal of a lesion does not eliminate the risk of creating embolithat may enter the vessel. The risk is particularly great when a secondballoon is used because the balloon is not advantageously placed for theremoval of emboli created by the use of the balloon itself and becausethe balloon must be removed by passing it across the lesion uponcompletion of a procedure. This drawback is present in all circumstanceswhen a balloon is advanced across a lesion because, when any occludingmember is placed distally of the lesion, the occluding member must bedrawn back across the lesion to remove the occluding member at the endof a procedure. Each passage of an occluding member across the lesion,even in a retracted or deflated state, carries a substantial risk thatadditional emboli will be produced.

[0007] Also, the placement of two balloons requires additional time toinflate the second balloon and adds to the complexity of a device due toan additional lumen that must be incorporated into the catheter toinflate the balloon. In a finite number of cases, the occluding memberthat is distal of a lesion, and is required to retain emboli in adefined area within the vessel, has been observed to fail, therebyreleasing the emboli into the bloodstream. Because the second balloon isrelied upon to prevent the flow of emboli past the region of the vesselcontaining the lesion, the failure of the balloon is a critical eventthat threatens the health of a patient undergoing the procedure.Furthermore, due to geometric constraints, the second balloon often actsas the guide wire as well. When delivering tools to perform thetherapeutic or diagnostic procedure within the vessel, the balloon maymove and disrupt the vessel wall. Introduction of tools and othermanipulations of a distally located balloon can also result in deflatingthe balloon or otherwise causing the balloon to lose patency on theinterior of the vessel.

[0008] Anytime that a balloon is placed distal to a lesion, the contactbetween the balloon and the lesion carries the risk of damaging thevessel. For these reasons, the use of balloons inside the vessel ispreferred to be minimized and the length of time and extent of contactbetween a balloon and the inside of a vessel should be reduced. Ideally,the balloon or other occluding member could be placed proximal to alesion so that the area containing the lesion would be isolated. Toachieve this, the irrigation and aspiration functions would have to beprovided by a structure that is positioned distal of the occludingelement, such that the occluding element could be placed proximal of thelesion, and the aspiration and irrigation functions achieved distal ofthe occluding member.

[0009] Even under existing technologies where aspiration and irrigationare applied in a catheter based system, the parameters of fluid flow, aswell as the placement of the aspiration and irrigation ports relative toan occluding member, are important to the physiological outcome for anygiven procedure. For example, removal of fluid and/or embolic particlesby simple suction from within a body conduit may only remove a portionof the fluid present in the vessel and may leave emboli in place even ifall of the fluid is removed and replaced. Deposits of plaque and otherdebris that may exist inside a vessel have a tendency to adhere to oneanother and particulate emboli tend to adhere to the sidewalls of thevessel. Thus, a system that provides limited fluid exchange isparticularly unlikely to achieve a complete removal of emboli. Also,given that the interior walls of a vessel may have been contacted fromwithin during a therapeutic procedure, a high likelihood exists thatadditional particles may be dislodged upon the establishment of a robustfluid flow through the vessel.

[0010] Ideally, a system for aspirating and irrigating the interior or avessel or organ would provide both fluid exchange and fluid flowparameters that are at least similar to that experienced during ordinaryphysiological functions and preferably would create a turbulent fluidflow that would proactively assist in the removal of particles and otheremboli. Such a system would require both a catheter element thatachieved aspiration and irrigation as well as a fluid exchange apparatusthat would be coupled with the catheter to produce the desired fluidflow rates and other fluid parameters. Because of the wide variation inintravessel procedures and the location of disease, an irrigation andaspiration system would also be particularly useful if the catheterelement could be selectively positioned along a specified length of avessel where emboli may be created together with operation of the fluidexchange apparatus to control the irrigation and aspiration flow. Thiscapability in the catheter element is most readily created with only asingle balloon system having a separate, movable, irrigation andaspiration catheter.

[0011] In the prior art two-balloon system described above, where aregion of a vessel is segregated by a pair of balloons located bothproximally and distally of a lesion, the area of fluid flow is limitedto the region defined by the placement of the two balloons. The problemis particularly acute when a vessel is treated with a procedure thatinstalls a stent or manipulates the plaque in a vessel, such as with anangioplasty, where the lesion is physically manipulated as part of thetherapeutic treatment. Assuming that the therapeutic treatment issuccessful, the vessel is treated by virtue of expanding the interiorvolume and promoting the flow of blood through the vessel. Under thesecircumstances, the portions of the vessel distal of the lesion have beencontacted by a balloon and are then exposed to a higher volume of fluidflow than existed before the procedure. In the context of a typicalpatient, a vessel which had become slowly blocked due to the deposit ofplaque over a large number of years has been expanded by the treatmentof the lesion and this therapeutic treatment at an upstream pointsubjects the region in which the lesion is located and those downstreaminternal portions to a rate and volume of blood flow that has not beenexperienced in the many years since the vessel began to become occluded.

[0012] Under these circumstances, an additional risk exists that plaqueslocated downstream from the lesion will be dislodged and will enter thecirculation causing serious injury.

[0013] As with ordinary irrigation and aspiration in an open surgery,the irrigation and aspiration that are applied through existing cathetersystems are typically regulated only by setting the positive or negativepressure that is applied to the aspiration or irrigation lumen of thecatheter and is in turn communicated to the distal end of the catheterto insert or remove fluid respectively. However, to create the specificfluid flow parameters that maximize the removal of emboli and the fluiddisplacement within a vessel, thereby establishing fluid change in thevessel in the most physiologically relevant manner, a specialized fluidexchange device would have to be created to regulate the fluid flowparameters of both the irrigation and aspiration functions of thesystem.

[0014] An ideal irrigation and aspiration system could be an additivecomponent to several other apparatus that are used in therapeutic,diagnostic, or imaging applications in the body such that the capabilityof the system would not be exclusive of other technologies that havebeen applied to enhance the safety of an intravessel procedure. Severaldifferent approaches apart from irrigation and aspiration have beenattempted to physically capture emboli downstream at a lesion, mostnotably through the use of filters. However, filters have inherentdrawbacks that cannot be completely eliminated. For example, embolicparticles smaller than the filter pore size, commonly on the order of100 microns evade filters, which must not be so small thatphysiologically important elements such as red and white blood cells arecaptured by the filter. Also, particles larger than the pore size tendto become trapped in the filter such that the filter itself becomes anocclusive element and blood flow through the filter is impeded. Also, asdescribed above for occluding structures, whenever a filter isintroduced distally to the lesion in a vessel, a finite probabilityexists that the removal of the filter will generate emboli. Stillfurther, where a stent is placed at a lesion, the movement of the filterpast the stent and through the vessel has the capability to catch ordisplace the stent.

[0015] Although certain portions of the discussion herein are directedtowards a preferred embodiment of the apparatus of the invention used inan intravessel procedure, the devices and methodologies of the inventioncan readily be applied to non-vessel sites within the body such aswithin any body conduit such as an ear canal, colon, intestine, thetrachea, lung passages, sinus cartilages, or any internal volume whereina controlled and localized irrigation and aspiration function aredesired. For example, in a diagnostic colonoscopy an endoscope may beintroduced to aid in optical visualization of the site. However, thecolon responds to fluid pressure changes and thus while trying to clearthe field the tissue of note may move. To aid in this diagnosticsituation, a controlled introduction of a clear fluid could beintroduced in concert with an equivalent aspiration of dirty fluid. Assuch, the tissue may remain in the field of view while the processoccurs. For imaging purposes the introduction of a contrast agent whilesimultaneously extracting an equivalent fluid will allow a vessel ororgan to maintain its normal fluid level and pressure. As the imaging iscompleted, the same system could then return a more normal fluid to thesite while extracting the foreign contrast agent. Imaging “pig-tail”catheters are presently used to introduce contrast agents to vascularsystem, even though radiopaque contrast agents are known to maintain alevel of toxicity (Solomon, Kidney International, 1998, vol. 53, pp.230-242). If the field of contrast was introduced and extracted asproposed by Courtney, et al., the patient's exposure would besubstantially reduced.

SUMMARY OF THE INVENTION

[0016] The present invention provides control of both irrigation andaspiration functions at a selected location within a body cavity orconduit, such as a target region of a blood vessel. The region of thevessel to which an irrigation and aspiration function are provided mayinclude both a therapeutic treatment site, the site proximal to theplacement of a balloon, or a length of a vessel both proximal to anddistal of a lesion wherein a surgical treatment was performed, where adiagnostic or therapeutic procedure caused the insertion of a dye orother solution, such as a clot dissolver, or where a total chronicocclusion occurs. Because the irrigation and aspiration functions areperformed simultaneously, the fluid exchange apparatus of the inventionis able to simultaneously regulate both irrigation and aspiration in amanner that advantageously controls the fluid flow rates and fluid flowparameters. This capability can be achieved both by controlling the flowrates using an electronic control system, as well as providing amechanical apparatus that controls irrigation and aspiration flows whenactuated by a user. When the catheter and fluid exchange device arecombined into the system of the invention, the combination providesunique capabilities for treating or diagnosing a lesion contained withina vessel. For example, the lesion may be pre-treated prior to thetherapeutic treatment which typically comprises ablation of a lesion orplacement of a stent or expansion of the diameter of the vessel, i.e.,through an angioplasty procedure. In a diagnostic embodiment, dye orother diagnostic markers can be infused distally of the occluding memberand proximate to the lesion while avoiding the potential hazards ofpassing a collapsed balloon across the lesion. This provides adiagnostic capability which has substantially reduced risk relative to atherapeutic treatment that requires expansion of an occluding memberdistal of the lesion. Because of the added safety margin, the diagnosticprocedures can be more readily performed without the risk of producingemboli and thus are a more available complement to the therapeuticprocedure.

[0017] Preferably, the system of the invention includes a catheterelement having specific features designed to facilitate the desirablefluid flow parameters when connected to the fluid exchange apparatus.Ideally, when coupled with an apparatus that inherently providescontrolled and regulated fluid flows for both aspiration and irrigation,the catheter works in tandem with the apparatus to create bothcontrolled and localized irrigation and aspiration through acatheter-based system. For example, the apparatus of the invention allowthe user to control the irrigation and aspiration flow volumes, and byvirtue of a specially designed catheter system, provide improved fluidflow parameters that facilitate quantitative volume exchange within avessel or other cavity and produce defined fluid flow parameters in aregion bordered by an occluding element. Accordingly, the aspiration andirrigation functions provided by the fluid exchange device can be addedto several existing devices such as balloon occluding elements orfilters, or can be used alone as a catheter-based fluid exchange systemwithout any additional device. Thus, the fluid exchange capabilities canbe added to an existing device such as a straight catheter or filter, oran existing device can be integrated into the remaining components ofthe present invention to provide the advantageous irrigation andaspiration functions as described herein. For example, to decrease timeduring a therapeutic or diagnostic procedure, the portion of thecatheter element providing the irrigation function could be combinedwith a catheter used to perform an angioplasty procedure.

[0018] When so integrated, the irrigation and aspiration finctions ofthe invention are located distal to the angioplasty balloon and theenhanced removal of emboli is facilitated. Also, the location of theirrigation and aspiration lumens can occur such that the aspirationports are on opposite sides of an occluding member or other structuresuch that a direct irrigant to aspirant volume exchange may or may notoccur in the lesion of a vessel. In preferred embodiments of the systemof the invention, the catheter element provides turbulent, rather thanlaminar, flow within the vessel. Turbulence is introduced locally at theregion of fluid exchange within the body. In a turbulent flow, thevelocity at a point fluctuates at random with high frequency and mixingof the fluid is much more intense than in a laminar flow. Turbulent flowis specifically preferred because it reaches the walls of a bodystructure and facilitates both fluid exchange and dislodging ofparticulate matter. To reach the walls, the irrigation ports exit thecatheter element in the direction of the wall. To accomplish this, thecatheter element preferably has ports that exit orthogonal to the wallof the distal end of the irrigation lumen of the catheter. Theaspiration lumen may establish a local laminar flow profile. Thisresults in laminar flow about the vessel.

[0019] Also, in a turbulent flow, the velocity at a point fluctuates atrandom with high frequency and mixing of the fluid is much more intensethan in a laminar flow. This is of particular value when attempting toclear any site of debris. Without turbulence, the flow along the sidesof a vessel/lumen is approximately 0. When trying to remove/clear orexchange fluids thoroughly is it imperative to facilitate mixing. Mixingcan only reach the vessel walls through the application of turbulence.This is appreciated by the vessels as well, since turbulence can beachieved with this invention without high-powered injection systems thatcarry physiological risks associated with their inherent power andabnormally high flow rates.

[0020] In more scientific terms, when a laminar flow is made turbulent,then the velocity will become more uniform and higher, and as a result,fluid particles in the boundary layer can move farther downstream beforeseparation takes place. This turbulence is generally local to theirrigation area and controlled by the dimensions and orientation of theports of the irrigation lumen.

[0021] The flow and velocity exchange rate through the entire system isnot altered significantly since the turbulence is local area around theirrigation ports. But turbulence for an equivalent flow produces a muchmore uniform flow across the vessel. This results in higher velocitiesalong the wall where emboli and thrombus are known to be in residence.From a physiological relevance standpoint, blood clots, or thrombi, aremuch more likely to be released into turbulent than in laminar flow.(Berne & Levy, 2001, Cardiovascular Physiology, p. 126).

[0022] Because flow is proportional to viscosity, irrigation with anynumber of fluids can increase the flow over just aspiration of the site.For example, the viscosity of blood is 5 times that of water in a vessellarger than 0.3 mm in diameter, (from graph 5-14, in Beme and Levy, p.129). The resulting combination of turbulence and the introduction ofvarious fluids allows for substantially variable fluid flows whichcannot be achieved without the combination herein disclosed.

[0023] Those of skill in the art will appreciate that the fluid exchangecapabilities and fluid flow parameters provided by the invention can beintegrated into a number of systems to provide irrigation and aspirationand essentially any physiological context where near quantitativeremoval of fluid or particles from a site is desired. As noted above,the enhanced fluid flow parameters can be strategically orientedrelative to the placement of an occluding member, such as a balloon, toeffectively remove fluids or solid matter either proximal to or distalof the occluding device. The catheter element of the apparatus can alsobe positioned to facilitate the removal of dyes, or therapeutic ordiagnostic compounds as part of the fluid exchange function of theapparatus of the invention.

[0024] In a preferred embodiment, the invention provides both irrigationand aspiration in a selected region of a vessel proximate to a lesion,but without any occlusion distal of the lesion such that the occludingelement may be both inserted and removed without passing across thelesion. Because of the design of the catheter-based system, a singlecatheter element may both aspirate and irrigate and may be moved withinthe vessel whether or not used in combination with other apparatus. Whenused in combination with an occluding element, the irrigation andaspiration factors may be fixed in place proximate to a lesion within avessel or may be movable such that a single catheter element having bothaspiration and irrigation functions can be advanced into an areaproximate a lesion and actuated to perform the irrigation and aspirationfunction both proximate to the lesion and distal to the occlusionelement. Similarly, if there exists a distal device (filter or occlusionballoon) this system can be activated to accomplish the followingoptimum clinical benefit. The irrigation ports being just proximal, butnot exclusively proximal, to the aspiration port, then the vessel can beirrigated actively with the local flow moving prograde. This drives theemboli up against a more distal occluder/filter and there the aspirationport evacuates the emboli. Used in concert with existing filters orballoons this results in optimum retrieval of emboli from the activeirrigation. This embodiment does not require a proximal occlusion forclinical benefit.

[0025] In procedures where emboli may be present, this device may beused as part of a method to extract the emboli generated during either atherapeutic, surgical, imaging or diagnostic procedure. The volumeexchange provided by the current invention is also adapted to facilitateremoval of fluids within a measured portion of a vessel where vesseldimensions and fluid volumes are known. This device affords a simplemechanical means through which these may occur in concert. Primaryapplications have been identified that produce a 1:1 exchange of fluids,but further applications include pulsatile exchange rates and ratiosother than 1:1.

[0026] The control aspect of the invention is derived in part frommeasured volumes that may be inserted and removed through a cathetersystem comprising an irrigation lumen and an aspiration lumen in fluidcommunication with irrigation and aspiration port(s) that insert andremove a defined or predetermined volume of solution. The design of thecatheter and the fluid flow parameters achieved at the target siteproduce specific fluid dynamics within a vessel or body conduit thatpromote the removal of emboli and/or the near quantitative removal of afluid contained in the region of a body conduit. In a preferredembodiment, a catheter coupled to a fluid exchange apparatus is actuatedto create turbulence within the vessel or organ and proximate to theports or exit holes of the irrigation lumen. As described in detailbelow, the size and orientation of the ports and lumen changes the fluidflow parameters such that defined flow rates, volumes, vortices,turbulence and ratios of fluids exchanged within the body can be customdesigned for any application, vessel, or organ, as well as for specificdiagnostic, therapeutic or imaging applications. Because many of theembodiments of the invention are used within the cardiovascular system,the irrigation and aspiration function can be designed such that fluidsmove into the vasculature in a pulsatile manner as with the movement ofblood within the vessel caused by the beating heart. This type of fluidmovement and fluid exchange provided by the aspiration and irrigationfunctions of the invention is advantageous because the insertion andremoval of fluid in this manner exposes the vessels or other structuresto fluid flow that is physiologically relevant. In the sense that thevessel experiences fluid flow that is similar to that experienced afterthe therapeutic, diagnostic, or imaging procedure is performed and anyemboli that would be released following the procedure are more likely tobe released during the irrigation or aspiration process performed by thedevices of the invention.

[0027] As described in more detail below, the design also facilitates adefined fluid exchange rate, such as 1:1 volume exchange that avoidsdamage to the vessel while producing turbulence to facilitate theremoval of emboli. Generally, turbulent flows provided by the device ofthe invention are localized and controlled in both volume and locationand are typically higher than that provided by the existing devices interms of both flow and velocity. Target flows of 1 cc/sec are relevantto vessels such as the vein grafts, flows up to 2 cc/sec are relevantfor vessels such as the carotids. (Louagie et al., 1994, ThoracCardiovasc Surg 42(3):175-81; Ascher et al., 2002, J Vasc Surg35(3):439-44).

[0028] As noted above, an advantage of the invention is the generationof localized turbulence in the vicinity of the infusion catheter suchthat volume exchange within the vessel promotes the disruption ofembolic particles that are only loosely attached to the interior wallsof a vessel. This advantage is derived from both the design of thecatheter, which affects the location in which fluids are inserted andremoved into a vessel or an organ, as well as the specific design andfunction of the fluid exchange apparatus that, when coupled with thecatheter of the invention, combine to produce improved fluid exchangeand fluid flow parameters. For example, in an ordinary vessel that isroughly cylindrical within a defined axial distance along the length ofa vessel, the removal of liquid generally produces a laminar flowthrough the center of the annular structure of the vessel and the fluidalong the walls of the vessel are largely left in place. With aturbulent fluid flow profile, the fluid introduced into the vesselcauses an exchange between the irrigant the existing fluid that islocalized along the vessel walls and generally causes a more thoroughmixing of the fluids within the vessel such that a more complete fluidvolume exchange occurs and the removal of embolic particles is enhanced.

[0029] Although the particular parameters vary according to the designsdescribed below, the fluid exchange achieved by the fluid exchangeapparatus and the irrigation/aspiration catheter results in an insertionand removal of a defined volume within a vessel. As described in furtherdetail below, the overall system is comprised of a fluid exchangeapparatus that may have a mechanical or electrical, or both, fluidexchange component that converts a defined volume of fluid exchange witha defined axial movement of the catheter such that the volume of fluidexchanged per measure of distance of axial movement of the catheterthrough a vessel is known. Preferred embodiments of the fluid exchangeapparatus are a substantially closed system wherein a reservoircontaining irrigating fluid is combined with a reservoir containing theaspirated fluid such that known volumes are exchanged through a systemthat is essentially “closed” except for the exchange site within thevessel. The terms “substantially closed” mean that the system is closedbecause the volume of fluid inserted as irrigant solution is removed asaspirant solution in a predetermined ratio and any deviance from theratio is attributed to only a volume of solution that is retained withinthe body at the target exchange site. For example, when a system of theinvention is applied to irrigate and aspirate fluid from within avessel, the system is substantially closed because the only differencebetween the fluid inserted as irrigant and removed as aspirant is thatwhich is purposefully left behind in the vessel. When the volumeexchange ratio of the device is set at a 1:1 ratio, the volumetricexchange of fluids is very near to equivalent. The fluid exchangeapparatus may also be actuated in such a manner that the flow producedby actuating the fluid exchange apparatus is a defined increment. Thus,a known volume of fluid is exchanged at the target site and theclinician knows with certainty the volume of irrigant fluid that isinserted as well as the volume of fluid that is aspirated out of thetarget site.

[0030] In one embodiment, the device of the invention provides a 1:1ratio of irrigation to aspiration fluid exchange such that the volume offluid introduced to a vessel or organ is exactly matched by the volumeremoved. Through control of the location and movement of the device ofthe invention, the interior of a vessel or organ can undergo a completefluid exchange by advancing the infusion catheter along the length of avessel where removal of fluid is desired. By this process, severalresults are achieved that are beneficial therapeutically. First, thevessel experiences a turbulence and a fluid flow that is physiologicallyrelevant in the sense that both the volume of fluid moving across avessel as well as the turbulence are similar to the parameters that thevessel would experience under blood pressure. This similarity hasseveral aspects. First, the turbulence that occurs in a vessel issimilar to the turbulence caused by the motion of blood moved by abeating heart. Second, the pulsatile nature of the fluid exchange isalso similar to the varying pressures and pressure profile caused byventricular contraction and the ordinary movement of blood throughoutthe arterial system. Finally, these specific fluid flow characteristicsare achieved without producing substantially increased pressures withina vessel and without distending the vessel through the application ofincreased fluid pressures. Thus, the combined irrigation and aspirationof controlled volumes of liquid treat the vessel with a physiologicallyrelevant fluid profile.

[0031] Because the device of the invention offers the ability tointroduce and remove a defined volume of fluid, the clinician can have ahigh degree of certainty that the entire internal volume of a region ofa vessel has been rinsed with an irrigation fluid by knowing theapproximate internal volume of the vessel and the length of the vesselin which irrigation and aspiration are performed. For example, assumingthat a specified region of a vessel has an internal volume of 20 ml overa defined axial length. The device of the invention can be used toinsert predetermined volumes of solution greater than, less than, orequal to 20 mls over the defined length of the vessel. Depending on theclinical environment, the ratio may be altered to remove greater volumeby establishing a smaller ratio of irrigation to aspiration. One could,for example, irrigate with one volume of solution while removing twicethe volume through the aspiration portion of the system to yield a 1:2irrigation to aspiration volume.

[0032] In a preferred embodiment, the fluid exchange device has theability to perform a controlled exchange of fluid with predeterminedratios including a 1:1 irrigation to aspiration ratio and varying ratiosparticularly values ranging between a 1:2 irrigation to aspiration ratioand a 2:1 irrigation to aspiration ratio. Preferably, this is achievedby having irrigant and aspirant reservoirs of defined volumes built intothe fluid exchange device. However, the device can also feature aselectable control that alters the ratio of fluid exchange between aminimum and a maximum as a function of the operation of the device. Inthe mechanical embodiment of the fluid exchange device, each actuationof the device may cause a defined volume of fluid to be propelledthrough an outlet that is in fluid communication with the irrigant lumenof a catheter element. In combination, the device also features anaspirant reservoir which is expanded by a predetermined volume relativeto the volume of the irrigant that is expelled.

[0033] The control of these parameters, in some aspects, by the fluidexchange device is the result of designing the fluid exchange device tocooperate with both conventional catheters as well as those speciallydesigned to produce turbulent flow at the target fluid exchange site.The fluid control functions of the exchange device can also cooperatewith the catheter element by incorporating the capability for the fluidexchange device to control motion of the catheter, specifically axialmovement within a body conduit such as a blood vessel. In thisembodiment, the catheter element is coupled to the actuation of thefluid exchange device by a coupled translation mechanism wherein, asdescribed in further detail below, each actuation of the device resultsin automatic advancement or retraction of the catheter. Thus, a definedexchange of fluid volume at the target site occurs in combination withadvancement or retraction of the aspiration and/or irrigation element ofthe catheter by a defined distance. In this manner, repeated actuationof the device provides a step-wise motion of the irrigation andevacuation functions and can insure a near quantitative volume exchangeover a defined distance. As will be apparent from the followingdescription, this aspect of the invention provides the ability to insertand/or remove a defined volume of fluid distal of an occluding membergiven an approximate knowledge of the dimensions of the vessel. As withthe other embodiments, the operation of the system may provide fluidexchange with a pulsatile fluid flow by virtue of the application anddissipation of pressure achieved through the catheter.

[0034] Any number of designs for the fluid exchange apparatus can beused to provide controlled volumes of irrigation and aspiration fluids,through the catheter element of the invention to the target exchangesite. The simplest embodiment of the invention provides a squeeze bulbwherein the irrigant and aspirant reservoirs are typically separated bya membrane and are in fluid communication with a irrigation andaspiration lumen that communicate fluids to and from the target site. Inthis embodiment, a one-way valve is provided preferably on both theirrigant and aspirant side of the fluid flow, to prevent aspirated fluidfrom flowing back to the target site. In another embodiment, amechanical device causes pressure to be exerted on an irrigant reservoirthat is in fluid communication with an irrigation lumen that providesfluid flow to at least one irrigation port at the distal end of acatheter. The catheter element also comprises an aspiration lumen, thatmay or may not be integral with the irrigation lumen, and whichfacilitates fluid communication of the aspirant fluid back to anaspirant reservoir. In this embodiment, the irrigant is expelled from areservoir by the application of mechanical force to reduce the volume ofthe irrigation reservoir and the mechanical force is preferably coupledto an expansion of the volume of the aspirant reservoir to yield adefined fluid exchange between the irrigant reservoir and the aspirantreservoir.

[0035] Those skilled in the art of medical devices will appreciate thatall of the component parts of the invention are assembled frombiocompatible materials, typically medical plastics or stainless steel.The syringes described below may be ordinary medical-use syringes or maybe custom fitted to be replaceable and to fit engagingly with the fluidexchange apparatus. An irrigant reservoir that is integral with thedevice may be pre-filled or a pre-filled syringe may be used to supplythe irrigant fluid. In either a stainless steel or plastic embodiment,the device is stabilized. Typically, stainless steel devices are exposedto heat and steam in an autoclave, while medical plastics may be exposedto gamma irradiation or microbicidal gases such as EtO. The methods ofthe invention specifically include the use of any component of thesystem of the invention followed by sterilization of the components, orthe entire system, and re-packaging for subsequent use. Although plasticembodiments are designed for single use, sterilization may be performedto functionally reconstruct the utility of the device after use with apatient.

[0036] In one preferred embodiment, a hand-held mechanical device isactuated by a trigger to insert and remove controlled volumes of fluidthrough the catheter element. The hand-held embodiment is comprised ofan actuator such as a movable trigger that is mechanically operated bybeing grasped by the hand and pulled towards a stationary structuralhousing of a complementary portion of a housing to cause a reduction inthe volume of an irrigant reservoir and, accordingly, fluid movementthrough an irrigation lumen and out one or more irrigation ports at thedistal end of a catheter. Fluid provided to the target site in thismanner is recovered through one or more aspiration ports andcommunicated through an aspiration lumen and returned to the aspirantreservoir of the fluid exchange device. The irrigant and/or aspirantfluids are preferably contained in a sealed reservoir system such as acylindrical chamber having a piston and a rod wherein the piston ismechanically coupled to the actuating element. Motion of the actuatingelement transfers force to the piston and causes contraction of theirrigant reservoir and expulsion of liquid from the reservoir.Simultaneously, the motion of the actuator causes the expansion of thevolume of the aspirant reservoir and causes withdrawal of fluid throughthe aspiration lumen and into an aspirant reservoir. In such anembodiment, the actuation of the trigger may translate into varyingamounts of fluid flow depending on the mechanical expedients used. Asingle actuation of the trigger may translate into an incrementalmovement of a piston that exerts force on an irrigant and/or aspirantreservoir. By the use of several conventional mechanical apparatus, suchas a ratchet and gear mechanism, a lever and pivot system, or others,the mechanical fluid exchange device exerts a direct control over theexchange of fluid communicated through the irrigation and aspirationlumens. The control of the fluid and the particular features can beprovided in several designs that achieve the same function. For example,in addition to the hand-held apparatus described below, the force neededto create the fluid flow in both the aspiration and irrigation sides ofthe system could be provided by a mechanical foot pump, vacuum pump orvirtually any component device that provides controllable fluid flow.Moreover, to provide total reproducibility in the operation of thesystem, a console controlled by a computer with appropriate commands ora software program is readily used to produce the same fluid flows,fluid exchange parameters, including exchange ratios, and essentiallyall of the functions of the purely mechanical embodiments describedbelow. Therefore, those of ordinary skill in the art will appreciatethat any number of mechanical or electrical variations give rise to thesame fundamental principle wherein controlled volumes are applied to atarget site through a segregated irrigation and aspiration system,preferably comprised of irrigation and aspiration lumens that passthrough at least one catheter element and engage in fluid exchange at atarget exchange site by virtue of specially designed irrigation andaspiration ports at the distal end of the catheter element.

[0037] By altering the dimensions of the irrigation reservoir and theaspiration reservoir, the ratio of fluid exchange between the irrigantand aspirant reservoirs is altered and, accordingly, the fluid exchangein the target vessel is adjusted. For example, where the irrigantreservoir and aspirant reservoir are of identical sizes, an actuation ofthe fluid exchange device may yield a 1:1 fluid exchange within thetarget vessel. Where, as described above, a different fluid exchangeratio is desired, the difference in the ratio may be achieved by acorresponding difference in the dimensions of the irrigant and aspirantreservoirs that are emptied and filled through the operation of thefluid exchange device. Also, variations in ratio may be accomplished bycorresponding changes in the dimensions of in-line chambers as describedbelow. Likewise, with a 1:1 ratio, equal volumes of irrigant andaspirant are exchanged in a single cycle of the fluid exchangeapparatus. In the 1:1 embodiment, the entire irrigation and aspirationvolumes may be exchanged within a defined number of cycles of theapparatus. For example, one may provide that each cycle of the hand-heldapparatus provides 1 ml of irrigant volume and removes 1 ml of aspirantvolume. By providing an irrigation and aspiration reservoir with knownvolumes, a known number of cycles translates into a known volume ofirrigation and aspiration. As noted above, in one specific embodiment,the actuation of the device also causes translation of the infusioncatheter along a defined axial path such that a known volume of solutionis provided in both the irrigation and aspiration aspects as a functionof the distance that is traveled by the infusion catheter.

[0038] Clearly, the irrigation reservoir may advantageously be dividedinto subparts and is not limited to ordinary aqueous solutions used in asurgical context. Given the utility of the present device for diagnosticand imaging applications, the irrigation reservoir could be filled withdyes, contrast agents, or other solutions that aid in the diagnosis ortreatment of the vessel. Given that the fluid exchange device of theinvention also provides unique fluid flow parameters, the irrigationreservoir could contain therapeutically valuable solutions such asheparinized ringers lactate, streptokinase, urokinase, tissueplasminogen activator, or other thrombus or emboli treatment fluids thatare used to perform the therapeutic procedure on the internal portion ofa vessel or organ. Given the ability to specifically tailor the fluidexchange parameters for a target vessel, the device offers the abilityto use therapeutic compounds that might not otherwise be availablebecause the clinician can be certain of the enhanced ability to removesolutions introduced via the irrigation reservoir. The fluid exchangeapparatus can also be used to promote absorption of a therapeutic layeron a vessel wall. If a drug coated stent is produced that can reabsorbdrugs after they have eluted, then with this device a high concentrationof the drug can be introduced and pooled about the stent for a briefperiod. This high dose may then be absorbed or bonded back to thestructure or one of its components and thereby recharging the drugcoated stent.

[0039] Finally, in a system where it may be advantageous to have ratiosother than 1:1 in the system it is also directly applicable. Forexample, in another vascular situation a virtual shunt may be createdwhere a proximal fluid can be circulating and a fluid is infuseddistally. This would involve a ratio of greater than 1:1 irrigation toaspiration. Furthermore such an arrangement could introduce a secondfluid to be the primarily distally delivered fluid. The second fluidcould be blood, blood substitute, plasma or oxygenated fluid to producea virtual shunt.

[0040] In the diagnostic use of optical coherence tomography, OCT, thefields of applications are presently limited by the need for a clearfield. Similarly the use of intravascular ultrasound, IVUS, is somewhatlimited by the attenuation associated with the blood in vivo. Asubstantial volume exchange of the vessel region in proximity of thedistal end of the OCT or IVUS catheter would provide the opportunity toreplace blood or other fluids with transparencies other than that foundin blood, thus improving and/or modifying the imaging quality.

DESCRIPTION OF THE DRAWINGS

[0041]FIG. 1 shows the basic components of the device necessary forimplementation with the optional inclusion of components that generate aminimum flow rate of exchange, components that incorporate an upper flowrate of exchange, and a configuration where a combination of flowthreshold and ceiling provide a flow rate bandwidth.

[0042]FIGS. 2A-2D are cross-sections of a vessel showing the catheterelement of the invention with aspiration and irrigation lumens combinedin the same catheter element and terminating at an aspiration andirrigation port, respectively. FIG. 2A is a section of the cathetershowing the aspiration and irrigation lumens. FIG. 2B is insertion ofthe catheter element into an exchange region established at a terminallumen characterized by a total occlusion such as a clot, lesion,abscess, a ball of wax or a body conduit or organ that is closed-endedsuch as an ear canal. FIG. 2C shows a cross-section of the system withan occlusion balloon to establish a defined region of fluid exchangebetween the irrigation lumen and the aspiration lumen. FIG. 2D shows oneexample of the placement of an aspiration port and an irrigation portthat is in fluid communication with the aspiration lumen and irrigationlumen, respectively.

[0043]FIGS. 3A-3F show the catheter element in various configurationsand illustrate the difference between laminar and turbulent flow. FIG.3A is a catheter element having an occlusion member and comprising anoccluding guiding catheter having an aspiration lumen and with theirrigation provided by a separate catheter to aid in defining a field ofexchange. FIG. 3B shows a catheter element providing an isolated,localized region for fluid exchange that is maintained by irrigationoccurring both proximal and distal to a centrally disposed aspirationport. FIG. 3C shows a typical laminar flow that fluids will naturallyassume when passing through a cylindrical tube. The flow velocities arehighest at the center of the tube and approach zero velocity at thewalls of the tube. The length of the arrows indicate the magnitude ofthe velocity.

[0044]FIG. 3D shows the turbulent region of flow created by a catheterelement of the invention adjacent to a region where the flow transitionsto a laminar flow, but still has a comparatively higher velocity alongthe walls of the tube. At a distance from the irrigation ports, the flowachieves laminar flow.

[0045]FIG. 3E shows a catheter element with 3 rows of perfusion holes.The figure illustrates how the turbulent flow is most pronounced in theimmediate vicinity of the infusion ports and begins to assume laminarcharacteristics until the next row of infusion ports is encountered. Inthe region designated “A,” turbulent flow is provided by the irrigationport geometry. In region “B,” flow is tending toward laminar flow. Inregion “C,” laminar flow is established.

[0046] In FIG. 3F, the various regions of flow show the relativedistances necessary for each activity. The transition region hastypically been shown to be about the same length as the perforatedregion of the catheter element.

[0047]FIG. 4A is a schematic of an embodiment of the fluid exchangedevice that produces pulsatile flow through the application of leverageto a hand-held unit that is actuated to communicate force to theirrigant reservoir and which collects fluid in the aspirant reservoir.FIG. 4B is an embodiment that accepts interchangeable fluid cartridges,similar to syringes, for irrigation and aspiration and where theexchange rates can be altered to other than a 1:1 ratio. In this examplethere is a 2:1 ratio of irrigant to aspirant dictated by the relativesizes of the fluid cartridges.

[0048]FIG. 5A is a fluid exchange device incorporating a segregateirrigant reservoir that uses different types of irrigants, while FIG. 5Bsegregates the irrigant fluid into a sample to be inserted both proximalto and distal at a point of the target site.

[0049]FIG. 6 is a tabletop version of the fluid exchange device that issuitable for either a mechanically drive hand system or anelectronically controlled, pump-driven system, including an optionalin-line air trap for the irrigant and a filter for the aspirant.

[0050]FIG. 7A and 7B are a grip lever activated embodiment of thehand-held fluid exchange device of the invention wherein the actuationof a trigger relative to the body of the handle translates into themotion of a piston that propels fluid from the irrigant chamber andcollects fluid in an aspiration chamber (not shown).

[0051]FIG. 8 is a preferred embodiment of the hand-held fluid exchangeapparatus of the invention having a spring tensioned trigger mechanismthat is actuated by manual motion of the trigger relative to the body ofa handle. Actuation causes linear or incremental motion of a dedicatedirrigant and aspirant carriage that move in opposite directions tocontrol the force supplied to the irrigant and aspirant reservoir,respectively.

[0052]FIGS. 9A and 9B illustrate an embodiment at the hand-held fluidexchange device having an adjustable pivot point on a trigger to producedifferent flow rates and peak pressures.

[0053]FIG. 10 is an embodiment wherein the control of the movement ofpistons that propel fluid from a cylindrical irrigant reservoir and intoan aspirant reservoir is provided by a ratchet mechanism.

[0054]FIG. 11 is a fluid exchange device with two chambers, such thatboth an irrigation and aspiration chamber are arranged to operate inconcert, with one filling and one expelling fluid in each direction andhaving separate input and output pathways for connecting to thereservoir and lumen elements.

[0055]FIGS. 12A and 12B show the apparatus configured as a compressibleball squeezed by the hand with the internal volume divided into irrigantand aspirant chambers and designed to be connected in-line withirrigation and aspiration lumens and reservoirs.

[0056]FIG. 13A and 13B are an embodiment wherein the fluid exchangedevice is a hand ball pump configured with an internal reservoir ofirrigant fluid and a flexible member to separate the irrigant fromin-flowing aspirant fluid. This device is initially loaded with a volumeof irrigant that encompasses most of the initial internal volume of theball and which flows through the target site to the internal aspirantreservoir. FIG. 13C is an embodiment having a substantially rigidexternal housing and an internal balloon. The interior of the housing isfilled with fluid and an internal balloon containing air or anon-volatile gas. A volumetric pump changes the internal configurationof the balloon to force fluid from an internal irrigant reservoir to aninternal aspirant reservoir.

[0057]FIG. 14 is a device with both irrigant and aspirant chamberscombined into one housing separated by a movable piston into twodistinct chambers to allow for the simultaneous rinsing and aspirating.

[0058]FIG. 15 shows a slidable and threaded combination configurationwhere an irrigant can be driven out and an aspirant simultaneously drawnin by both a sliding and a screw-type mechanism. The sliding providesgross travel and the rotation of the member about the axis produces afine-tuning mechanism.

[0059]FIG. 16 is an embodiment of the fluid exchange device that can becomprised of as few as the structural elements that preferably attach toa cylinder body of one reservoir and piston of the other.

[0060]FIGS. 17A and 17B are a mechanical fixture for providing aself-advancing or retractors catheter element in combination with thefluid exchange device.

[0061]FIGS. 18A-18C are an embodiment of the invention with a stagingcapability such that the means for aspiration and irrigation are linkedmechanically to travel in equivalent and opposite directions.

DETAILED DESCRIPTION OF THE INVENTION

[0062] The present invention may be used in a number of differentenvironments and for a variety of purposes including, but not limited toall physiological uses of peristaltic or other pump for aspiration andirrigation including, IVUS, OCT, angioplasty, endortarectomy, cardiacstent placement, vessel treatment, diagnosis and repair, surgicalplacement of non-cardiac stents, insertion of pig-tail catheters, earrinsers, etc. The following detailed description is exemplary ofpossible embodiments of the invention.

[0063] Referring to FIG. 1, a schematic representation of the inventionshows the basic components of the device necessary for implementation.The core fluid exchange or activation system maintains a substantiallyclosed loop system with the target site for fluid exchange, e.g. thesite within the body where aspiration and irrigation are applied. Theirrigation component of the invention is conveniently provided by adedicated irrigation reservoir 1, particularly when the fluid exchangesystem is the mechanical embodiment described in greater detail below.The exchange site is in fluid communication with the fluid exchangesystem via the irrigation lumen 2 and the aspiration lumen 3 which haveexit or entry ports (not shown) at the distal end of each lumen. Theaspiration component may also feature an aspiration reservoir 4 in fluidcommunication with the aspiration lumen 3 and aspiration ports (notshown) such that fluids removed from the exchange site are stored in theaspiration reservoir 4. As is apparent to one of ordinary skill in theart, the irrigation 1 and aspiration 4 reservoirs may be controlledelectronically by valves or pumps to provide the controlled fluidexchange ratios described herein. Thus, while the embodiments of theinvention featuring fluid exchange apparatus that are mechanicallycontrolled by the user are preferred in certain versions of any system,controlled rate of fluid exchange at a target site may be used in asystem of the invention. Alternatively, fluids in the aspirationreservoir 4 may be discarded. In one embodiment of the invention, fluidscommunicated from the target exchange site through the aspirationcomponent of the invention are analyzed for chemical or particulatecontent to determine a level of removal of fluids or solid matter fromthe exchange site.

[0064] Referring again to FIG. 1, an optional configuration of the.components includes a flow valve 6 that produces a minimum lowerthreshold for irrigation flow. This minimum delivery flow is beneficialto ensure a minimum amount of exchange flow when the clinical indicationdictates maintaining a minimum flow through the irrigation catheter. Theflow threshold insures that the fluid exchange does not fall below apredetermined ratio as described herein. For example, although 1:1 fluidexchange rates are provided in several embodiments described herein, theexchange ratio may be altered such that a larger volume of fluid isaspirated compared to that which is used for irrigation or vice versa.Under such circumstances, the fluid exchange ratio would vary to, forexample, a 1:2 irrigation to aspiration ratio under circumstances wherea larger volume of liquid is desired to be removed from the exchangesite.

[0065] The components of the invention could also incorporate an upperflow rate of exchange or flow ceiling 6. When conditions dictate thatthere is motivation to limit the velocity or overall flow parametersduring a usage, a configuration that provides an upper limit may beprovided. Accordingly, this embodiment would apply where a larger volumeof fluid was desired to be inserted by irrigation compared to that whichis removed by aspiration and the corresponding irrigation to aspirationexchange ratio would be increased to, for example, 2:1. The combinationof a flow threshold and flow ceiling capability provide a flow ratebandwidth yielding a range of values between two extremes. In thisembodiment, the exchange site can be irrigated and aspirated at aconsistent level that is either fixed or varies within a range. This mayalso allow the activation system to sustain a change in the pressurelevel at the exchange site while delivering irrigant fluid or removingaspirant fluid at a steady rate or within a range of rates. As will beappreciated by one of ordinary skill in the art, the irrigation side ofthe system of the invention requires active force provided by the fluidexchange apparatus such that irrigant fluid flow is established at thetarget site. However, while the aspiration side may also be controlledthrough application of force to withdraw fluid from the target site, theaspiration side may also be passive such that the inherent pressure atthe target site propels the aspirant fluid. The inherent pressure istypically provided both by the fluid pressure inside the body, e.g. theblood pressure within a vessel, and the pressure of the irrigant fluidentering the target site. This characteristically passive flow may bedescribed as an efflux flow, see U.S. Pat. No. 4,921,478 which isspecifically incorporated by reference herein. The passive flow ofaspirant fluid is one way through the aspiration lumen and the fluidpathway is comprised of one-way valve, such as conventional duck billvalves having a minimal cracking pressure to allow passive fluid flowwhile preventing retrograde flow through the aspiration side of thesystem. This capability provides for constant extraction of embolicparticles throughout a clinical procedure while irrigant fluid flow ismaintained and/or when fluid existing at the target site flows fromendogenous body pressure.

[0066]FIG. 2A is a cross-section of a catheter element 7 of theinvention at the exchange site. The irrigation lumen 2 in thisconfiguration terminates at or proximate to the distal end of thecatheter element. While the aspiration lumen 3 terminates proximally andboth lumens terminate with exit ports 8,9. FIG. 2B depicts the insertionof fluid into an exchange region at a terminal lumen. The irrigationport 6 in this depiction is dislodging a terminal occluding clot. Theterminal occlusion may include but is not limited to a clot, lesion,abscess, a ball of wax or an ear canal. In such situations, simpleaspiration may not eliminate the lesion and a non-traumatic irrigationof the lesion with a therapeutic formulation, in concert with aspirationafter an improved treatment methodology. For example, even if theirrigation fluid is able to produce a substantial breakdown of aterminal occlusion, the occlusion itself must still be cleared.Moreover, the combination of irrigation and aspiration to yield fluidexchange after the ability to introduce pharmaceutical agents proximateto the occlusion and the ability to remove the agents before they enterthe bloodstream. A specific example of this is a thrombolytic agent usedto remove the occlusion or potentially dangerous thrombus, wherein thethrombus or occlusion must be both treated and removed to treat thecondition and wherein the necessary dosage of the agent exceeds thatwhich could otherwise be introduced without drug-related toxicity.

[0067]FIG. 2C is a cross-section of the catheter element of the systemincorporated with a proximal occlusion balloon 11 to establish a definedregion of fluid exchange. This configuration may be useful for, but isnot limited to, occluding flow, limiting a diagnostic agents field ofdeployment or limiting the bodies exposure to a high intensity agent. Adedicated balloon lumen 12 is provided for inflation of the occludingdevice. FIG. 2D is the catheter element of the system of the inventionhaving an occlusion member 11 to aid in establishing an exchange siteand having irrigation and aspiration functions distal to the occludingmember wherein the arrows depict the general direction of fluid flow,distal to proximal, relative to the occluding member 11.

[0068]FIG. 3A is the device incorporated with a combined aspirationlumen 3 and occluding element 11 integral in the same catheter elementwith the irrigation driven by a separate catheter 2 to aid in defining atarget site or field of fluid exchange. The irrigation lumen's 2independent travel affords a means of adjusting the location of thefluid exchange site while maintaining the occlusion at a predeterminedlocation. Furthermore, a treatment, diagnostic or imaging tool (notshown) can also be affixed to the irrigation catheter 2. This isproductive where the resident fluids are desired to be replaced with adye or contract agent and then removed in turn prior to re-establishingnormal blood flow. In optical coherence tomography (OCT), for example,it is advantageous to introduce and remove a low attenuating fluid. FIG.3B is a fluid isolated region that is maintained by irrigation occurringthrough ports 8 located both proximal and distal to the aspiration port9. This configuration presents a means of maintaining a controlledintroduced field of fluid between the proximal and distal irrigationports 8. As in the embodiment of FIG. 3A, a treatment, diagnostic orimaging tool could be attached or moved along in concert between theirrigation ports. Referring to FIG. 3C, a catheter element (not shown)that merely inserts and removes fluid from a vessel achieves onlylaminar flow in the direction of the arrows and with velocityillustrated by the size of the arrows. Near the vessel wall the totalfluid flow approaches zero such that fluid containing emboli at thewalls is not disturbed and loosely affixed emboli remain in place. FIG.3D is a preferred embodiment of the catheter element of the inventionhaving orthogonally disposed aspiration ports 8 located at the distalend of the catheter element 7. The region “A” experiences turbulentflow, while region “B” experiences a flow profile that is in transitionfrom turbulence to laminar flow. FIG. 3E shows a series of irrigationports 8 spaced at intervals along the length of the distal end of acatheter 7 such that either turbulent flows, designated as “A” orregions where turbulence is transitioning to laminar flows, designatedas “B” are established along a length of the catheter 7 to substantiallyeliminate areas of laminar flow. FIG. 3F shows a configuration whereinthe irrigation ports are provided as a perforated region 8′ at thedistal end of the catheter 7. The arrows indicate the direction andmagnitude of flow showing that the perforated region establishesturbulence in a defined region, and as the distance away from theperforated portion 81 increases, the flow reverts to a laminar flow at acertain distance along the length of the vessel.

[0069]FIG. 4A is an embodiment of the device 10 that produces pulsatileflow through the application of a mechanical force to an apparatus thatpropels fluid through the catheter element of the invention. In use, theaction of a trigger 20 pulled toward a handle 21 exerts a force on adedicated irrigant piston 22 that compresses the irrigant reservoir 1thereby reducing the volume of the irrigant reservoir 1 and forcingfluid through the irrigant lumen (not shown) and simultaneouslywithdraws the dedicated aspirant 23 piston of the aspirant reservoir 4to accomplish the fluid exchange at the target site. Actuation of thetrigger 20 may cause the relative motion of the pistons 22, 23 byconnection handle to a ratchet or other gear mechanism that provides theexertion of force in an incremental amount based on the actuation of thehandle in a cyclical fashion. See e.g. FIG. 10 below and accompanyingtext. As shown in FIG. 4A, the irrigant and aspirant reservoirs mayadvantageously be provided by conventional syringes or similar devicesthat provide for fluid containment and the controlled application offluid flow. The syringes of FIG. 4A are merely examples of the use ofreplaceable cartridges that may be readily inserted and removed from thedevice. Such cartridges are particularly useful when pharmaceuticallyactive solutions are pre-filled and used in specific clinical procedureswhere medicaments are provided to a body conduit or vessel by the systemof this invention. In this respect, the use of this invention allows theselective introduction of pharmaceutical compositions of any type duringthe performance of an ordinary irrigation and aspiration operation. Inthe embodiment of FIG. 4A, the syringes comprising the irrigantreservoir 1 and aspirant reservoir 3 may be removably inserted into thehand-held fluid exchange apparatus 10 and used to both provide and expela predetermined volume of fluid through the target exchange site. Inthis manner, both the volume and content of the irrigant fluid can becontrolled by exchanging syringes and the contents of the aspirantreservoir can be retained and analyzed for fluid or particular content.The operation of preferred embodiments of the hand-held embodiment ofthe invention is also described at FIGS. 7-10 below and the accompanyingtext.

[0070]FIG. 4B is an example of interchangeable fluid cartridges 24 a 24b, similar to the syringes described in other embodiments, forirrigation and aspiration. As described in greater detail herein, theirrigant 1 and/or aspirant 3 fluid reservoirs may be provided bycartridges or reservoirs of differing sizes to accomplish thepredetermined volume exchange ratio desired for the particular clinicalindication. In the embodiment of FIG. 4B, the irrigant fluid cartridge24 a has double the volume of the aspirant cartridge 24 b therebyproviding a 2:1 fluid exchange ratio of irrigant to aspirant at thetarget site. In this respect, the loop established by the fluid exchangesystem is not a completely closed loop, but is described as asubstantially closed loop, in that a difference exists between thevolume expelled through the irrigant reservoir 1 via the irrigant lumen2 and into the exchange site versus the difference in the aspirantvolume taken up through the aspirant lumen and into the aspirantreservoir 40 although the volumes are not identical, the volumes arepredetermined and known with certainty as is the volume of fluid thatremains at the target site, which is the difference between the volumeof the irrigant fluid introduced to the site and the volume of theaspirant fluid removed therefrom. As in the embodiment of FIG. 4A, theirrigant fluid cartridge 24 a has a dedicated piston 22 for expellingfluid from the cartridge. The aspirant cartridge 24 b similarly has adedicated piston 23 for collecting fluid introduced to the aspirantreservoir via the aspiration lumen 3. In this specific embodiment, moreirrigant fluid is introduced due to the larger cross-section of theirrigant cartridge 24 a while the overall length of the cartridge thatfits into the fluid exchange apparatus remains constant. This techniquefor providing varying fluid cartridge volumes is advantageous when theirrigant and aspirant cartridges are replaceable in a fluid exchangedevice.

[0071]FIG. 5A is a revolving cartridge 25 that can rapidly provide aseries of irrigant solutions. This revolver-style orientation ofirrigant solution is advantageous for delivery of a sequence ofdifferent fluids or for delivery of a pharmaceutical composition at anintermediate point during a procedure. In use, the revolving cartridge25 is oriented such that the series of irrigant fluids 24 b, 24 c, 24 dare positioned in line with the dedicated irrigant reservoir piston 22to expel the selected irrigant solution placed in line with the piston22. Under certain clinical circumstances, the application of the systemof the invention may provide an ordinary rinsing solution such as salineat the beginning of a procedure to clear resident fluids and/or embolifrom a site, followed by the introduction of a pharmaceutical solution,followed by the removal of the pharmaceutical solution and thesubsequent introduction of a neutral solution. In such a use, the salinesolution would be confined in the first irrigant reservoir 24 b, whichwould be infused by actuating the handle 20 as in the embodiment of FIG.4A described above. Subsequently, the contents of the second irrigantreservoir 24 c, such as a thrombolytic agent, dye, contrast agent orother formulation, is inserted by rotating irrigant reservoir 24 c inline with the irrigant reservoir piston 22, and similar actuation oftrigger 20. Once the desired effect provided by the solution ofreservoir 24 c has been achieved, the solution may be rinsed from thevessel by rotating the dedicated irrigant reservoir 24 d into place andactuating the fluid exchange system as above. Similarly, a variety ofaspirant chambers (not shown) can be used to facilitate collection andtesting of the aspirant fluid by segregating discrete volumes intocontainers that can be processed for analysis.

[0072]FIG. 5B is an embodiment where two different irrigant fluids canbe delivered at equal time and measure in a pair of cartridges 243, 24 fthat are designed to be delivered through one or a pair of irrigantlumens 2, 2′ such that one irrigant lumen 2 delivers fluid distal to apredetermined point at the target site and the other irrigant lumen 2′delivers fluid proximal to a predetermined point at the target site. Insuch a case, each of the two irrigant lumens 2, 2′ has a dedicatedirrigant port or ports located at the distal end of the catheterelement. The division of the irrigant reservoir 1 into two components 24e, 24 f allows for the selective introduction of irrigant fluids, whichmay be the same solutions or different solutions at two or more pointswithin the target site. The predetermined point in the target site thatseparates the proximal and distal delivery of irrigant fluid may be anaspirant port located therebetween (as in the embodiment of FIG. 2D) orany other structure where separation of irrigant fluid is desired. Forexample, some irrigants may mix advantageously only at the exchange siteand could not be combined outside the body based on their chemicalreactivity.

[0073]FIG. 6 is a tabletop version of the fluid exchange device of theinvention. As is described elsewhere herein, the fluid exchangeapparatus of the invention may be controlled by the simple mechanicaloperation of a device by a user or by an electronic system that controlsa mechanical or electrical pump- or valve-driven system to control theirrigant 1 and aspirant 4 reservoirs. In the embodiment of FIG. 6, avariable position lever 30 drives the stroke of a dedicated piston 22,23 that forces fluid from the irrigant reservoir and draws fluid intothe aspirant reservoir. As with the embodiments described above, thecycle and the volume of the reservoirs or motion of the pistons can bealtered to match the fluid exchange volume needed for any flow in thevessel or body conduit. Because the rotation of the individual levers isvariable, the ratio of fluid exchange can be achieved by differentpositioning of the lever arms 31, 32 rather than by altering the volumeof the individual irrigant 1 and aspirant 4 reservoirs. Although thisembodiment shows the mechanical application of force through levers, atabletop version of the apparatus of the invention is advantageous whenelectronically controlled pumps are provided to control the fluidexchange and fluid exchange ratios. The embodiment of FIG. 6 also mayinclude an in-line air trap 33 for the irrigant reservoir 1 and/or afilter 34 for the aspirant reservoir 4. As it may be advantageous toeliminate debris upon extraction of irrigant fluid and/or prevent airupon entry of irrigant fluid, the inclusion of a filter or trap 33, 34for air and/or emboli is appropriate in some cases.

[0074]FIG. 7A and 7B show the internal structure and function of a fluidexchange device 40 where a pair of reservoirs control fluid flow via theforce exerted by pistons or plungers following the action of a trigger20 and handle 21 connected to or integral with a lever 36 that rotatesabout a pivot 35. In this embodiment, the actuation of the trigger 20rotates the level 36 about pivot 35 and forces the irrigant reservoirpiston 22 into the irrigant reservoir 1 and simultaneously withdraws theaspirant reservoir piston 23 out of the aspirant reservoir. From therelaxed position (FIG. 7A), the trigger 20 can be activated to drive thepistons 22, 23 through either a direct coupling or a mechanism forincremental cycles. If desired, the trigger 20 can return to the relaxedposition after a cycle from spring action in the handle or pivot 35other automatic return mechanism. The reservoirs may be integral to thedevice 10 or the volume of the reservoir 1 may be attached to a separatereservoir (not shown) together with the appropriate lumens, andpreferably in-line one-way valves, to facilitate the exchange betweenthe separate reservoir and the chamber of the device. In the formerembodiment, the reservoirs are integral to the handle-operated devicesuch that the piston exerts a direct force on the irrigant 1 and/oraspirant 4 reservoir to exert the force necessary for fluid exchange. Inthe above embodiment, the internal structure of the device acts as anin-line chamber that is intermediate between the separate reservoir andthe lumen such that irrigant fluid residing in a separate reservoir isdrawn into the chamber prior to being expelled from the chamber throughthe irrigation lumen. In this embodiment, a pair of lumens are required,a first intermediate lumen connecting the separate reservoir to thechamber, and a second lumen communicating the irrigant fluid from thechamber through the irrigant lumen and via the irrigant ports to thetarget exchange site.

[0075]FIG. 8 is a preferred embodiment of the invention having a trigger20 that is squeezed by the hand to operate a syringe that acts as theaspirant reservoir 54 and the irrigant reservoir (not shown). As thetrigger 20 moves toward the body of the handle 21, the force istransmitted both to the piston 55 dedicated to the aspirant reservoir 54and a separate piston (not shown) dedicated to the irrigant reservoir.Although the internal configurations can be varied to incorporate othermechanical expedients, the orientation of the lever 56 and pivot 62 ofthe present embodiment provide an advantageous mechanism for a 1:1 ratiofluid exchange. The action of trigger 20 is communicated to a lever 56that is connected to the trigger 20 by a first terminal lever connector58 a. When the trigger 20 moves toward the body of the handle 21, theforce exerted on the lever 56 rotates the lever 56 around pivot 57 toexert a force, via a second terminal lever connector 58 b that isattached to an irrigant carriage 52. Simultaneously, the motion of thetrigger 20 exerts force on a second lever (not shown) that is connectedto the aspirant carriage 51 in a similar matter as for the irrigantcarriage 52. The motion of the trigger 20 provides a simultaneous butopposite force on the aspirant cartridge 51 compared to the irrigantcartridge 52. The simultaneous forces that are applied to the pistonsdedicated to the irrigant reservoir and aspirant reservoir 54,respectively, occur in opposite directions to yield a substantiallyequivalent volume exchange into the aspirant reservoir 4 and out of theirrigant reservoir 1 via the aspirant and irrigant lumens 4, 2respectively. The motion of the irrigant carriage 52 is translated tothe piston dedicated to the irrigant reservoir by virtue of a connector53 that is noncompressible and that is aligned with the length of theirrigant reservoir 1.

[0076] As noted specifically with the embodiments described at FIG. 4Aherein, the irrigant and aspirant reservoirs 1, 4 may be interchangeablesyringes or cartridges that can be inserted and removed to introducespecific solutions or fluid volumes. In a preferred embodiment, theirrigant and aspirant reservoir 1, 4 may be molded into the body of thedevice such that the fluid volumes for the irrigant and aspirantreservoirs are separately filled via a fixture that acts as an inputvalve to the irrigant and/or aspirant reservoir. The irrigant andaspirant reservoirs 1, 4 preferably have removable fixtures at theoutput 60 thereof for attachment of the respective lumens 2, 3.

[0077] The motion of the trigger 20 is rendered linear and reproducibleby slots 61 cut into a portion of the trigger 20 that are engaged by thefirst pivot 57 and the second pivot 61 such that the body of the handle21 and/or the trigger 20 slidingly move about either of the pivotstructures. A second lever 63 operates parallel to the lever 56 toenable the trigger 20 to travel smoothly along its path. Thisconfiguration provides for reproducible motion of the trigger 20relative to the body of the housing 21 and also facilitates attachmentof a spring 62 that biases the trigger in the forward position so thatactuation of the trigger 20 relative to the handle 21 produces acomplete cycle that translates into a defined movement of both theirrigant cartridge 52 and the aspirant cartridge 51. The volume exchangeratio provided by the device of this invention may be altered bychanging the relative lengths of the lever 56 relative to the pivot 57or by altering a ratcheting mechanism disposed at the connection pointbetween the lever 56 and the irrigant cartridge 52 such that a completecycle of the trigger 20 from the forward most position when moved towardthe body of the handle 21 constitutes a complete cycle that moves theirrigant 52 and/or aspirant cartridge by fixed distance. The springtension automatically returns the trigger 20 to the forward mostposition to prepare for a second cycle.

[0078]FIG. 9A is an embodiment where the travel of the lever in thefluid exchange device is adjustable so that the amount of fluiddisplaced in a single cycle can be controlled, and both the distancetraveled and the force generated can be adjusted by relative positionsof the trigger 20 and the handle body 21. The embodiments of FIGS. 9Aand 9B illustrate the ability to alter the fluid flow parameters of thefluid exchange device by changing the configuration of the mechanicalcomponents that exert force on the irrigant reservoir 1 and aspirantreservoir 4, respectively. FIG. 9B illustrates the adjustment of thepivot point 57 a to produce different flow ratios and peak pressuresbased on the relative position of the pivot point 57 a about which thetrigger 20 rotates. In such an embodiment, if more fluid flow is desiredthe apparatus can be easily adjusted to accomplish a variable number offlows for a given grip cycle. The travel distance provided by the motionof the trigger 20 as exerted at the point of attachment by the secondterminal lever connector 58 c dictates the amount of fluid flow expelledfrom the irrigant and/or aspirant reservoir 1, 4 based on the action bya syringe or aspirant reservoir piston or carriage as described above.Accordingly, an increase in the motion of a piston compressing fluid inan irrigant or aspirant reservoir or chamber, due to changing the pivotpoint, results in an increased exchange rate for a given activation ofthe trigger 20. As is shown in FIGS. 9A and 9B, the adjustment to thedegree of travel of the trigger 20 relative to the handle 21, whencombined with aspiration 51 and irrigant 52 carriages and reservoirs asdescribed in, for example FIG. 8 above, produces the variable fluid flowof this embodiment. As with the embodiments described above, themechanical movement of the trigger 20 relative to the handle 21 istranslated into fluid flow from an irrigant reservoir 1, via irrigationlumen 2, aspiration lumen 3, and aspirant reservoir 4 by theconfigurations described herein.

[0079]FIG. 10 is a hand-held fluid exchange apparatus of the inventionwherein a ratchet mechanism provides for incremental movement of apiston, in this embodiment, a general set of pistons 71, 71 a fordriving fluid out of the irrigant reservoir 1 and into the aspirantreservoir 4, respectively. As in the embodiment of FIG. 8, the motion ofa trigger 20 relative to a body handle 21 completes one cycle. Thisembodiment may also contain a mechanical or electrical counter thatprovides a readout indicating the number of cycles that have beenperformed, the volume of fluid introduced or removed, or the amount offluid present, or remaining in either reservoir. In this embodiment, themotion of the dedicated, geared piston 71 in the irrigant reservoir 1 iscontrolled by the ratchet mechanism which is comprised of the trigger20, a pivot 70, about which the trigger 20 rotates, and gear 70 b thatengages a first ratchet wheel 77. Preferably, the ratchet mechanism isone-way such that motion of the trigger 20 toward the body handle 21rotates the first ratchet wheel 72 that rotates to advance or contractthe piston 71. In the example of FIG. 10, actuation of the trigger 20about pivot 70 a translates to rotation of the first ratchet wheel 72via gear 70 b. The rotation of the first ratchet wheel 72 is translatedto the geared piston 71 and this rotation is in turn translated to asecond ratchet wheel 73 that rotates in the opposite direction to thefirst ratchet wheel 72 that is in turn connected to a geared piston 71 ain the other reservoir.

[0080] In the embodiment of FIG. 10, the device is designed to behand-operated such that the manual actuation of the trigger 20 causesautomatic motion of the two ratchet wheels 72, 73 and the geared pistons71. The equivalent dimensions of the reservoirs 1, 4, pistons 71, 71 a,and the two ratchet wheels 72, 73 shown in FIG. 10 yields an approximate1:1 fluid exchange ratio. In addition to altering the dimensions of theaspirant 4 or irrigant 1 reservoirs, the alteration of the fluidexchange ratio can be achieved by altering the dimensions of the ratchetwheels 72, 73.

[0081]FIG. 11 shows the principles of a fluid exchange device with asegregated irrigant 75 and aspirant chambers 76 each having a dedicatedinflow and outflow line. In this embodiment, the inflow line of theirrigation chamber 75 is an irrigation inflow line 2′ that communicatesfluid held in the irrigation reservoir 1 to the irrigation chamber 75.The fluid is drawn into irrigation chamber 75 by the dedicated piston 22and is subsequently expelled through the irrigation lumen 2 into thetarget site for fluid exchange as described previously. Similarly, fluidis drawn from the target site through the aspiration lumen 3 and intothe aspiration chamber 76 by operation of the dedicated piston 23 whosemotion both pulls fluid through the aspiration lumen 3 and into theaspiration chamber 76, but also expels fluid from the aspiration chamber76 to the aspiration reservoir 3, via the aspiration reservoir outflowline 3′. This embodiment of the invention operates much like atwo-stroke engine wherein fluid is pulled into the irrigation 76 andaspiration 75 chambers and. subsequently expelled through theappropriate lumen. To control the flow of fluids, each of the dedicatedinflow and outflow lines for each chamber have valves 77 a, b, c, d thatcontrol the fluid flow. For example, when fluid is drawn into theirrigation chamber 75, a valve 77 a on the chamber inflow line 2′ isopened while the piston 22 is pulled back. Subsequently, the inflowvalve 77 a closes and an outflow valve 77 b that is in line with theirrigation lumen is opened while the irrigation chamber piston 22 isforced into the irrigation chamber 75 to expel fluids through theirrigation lumen 2. Similarly, when the action of the aspiration chamberpiston 23 is used to draw out fluid into the aspiration chamber 70 viaaspiration lumen 3, an inflow valve 77 d on the aspiration chamberinflow line 3 is opened and the in-line valve 77 b in the aspirationchamber outflow line 3′ is closed. To expel fluid from the aspirationchamber 76 through the outflow line 3′ and into the aspiration reservoir4, the in-line valve 77 d on the aspiration lumen 3 is closed and thein-line valve 77 c on the aspiration reservoir outflow line 3′ isopened. As for the embodiments described above, the action of theindividual pistons 22 and 23 used to cause the fluid flow throughout thesystem can be controlled manually by mechanical expedients affixed tothe pistons. Alternatively, electronic circuitry can control the speedmotion and cycle parameters of both pistons such that the fluid flow iselectronically controlled according to a user interface or apredetermined fluid exchange profile. As will be apparent to one ofskill in the art, the cycling action of this embodiment produces apulsatile flow with the relative motion of both pistons 22, 23.Moreover, the particular minimum and maximum pressures in each pulsatileflow can be controlled by the relative action of the pistons 22, 23.

[0082] In another embodiment, the in-line valves are not activelycontrolled, but are provided as simple one-way valves that only allowfluid inflow from the irrigation 1 reservoir into the irrigation chamber75 and, likewise only allow fluid outflow from the irrigation chamber 75through the irrigation lumen 2. On the aspiration side of the system,one-way valves allow fluid flow only from the aspiration. lumen 3 to theaspiration chamber 76, and from the chamber 76 to the aspirationreservoir 4. In use, when the device is activated, the piston plunger ineither chamber will produce a positive flow through the lumen. When thelever begins to relax, the one-way valve will close and the irrigationreservoir 1 will fill the chamber. On the aspiration side, one-wayvalves on both the lumen 3 and the reservoir 4 ensures that the aspirantfluid is purged into the reservoir and, during relaxation, the aspirantis extracted from the exchange site via the aspiration lumen 3.Actuation of the pistons simultaneously causes simultaneous fluid flowto and from the target site while a ½ cycle out of phase yields atransient pressure increase within the system.

[0083]FIGS. 12A and 12B show a hand-held fluid exchange apparatusconfigured as a compressible handball with the internal volume dividedinto irrigant and aspirant aspirant chambers 78, 79 in series withdedicated inflow and outflow lines connecting irrigation 1 andaspiration 4 reservoirs, respectively. With a fluid impermeable walldisposed between the irrigant 78 and aspirant 79 chambers, the collapseof the ball under force will circulate the fluids appropriately.Referring to FIG. 12A, the apparatus is divided into an irrigationchamber 78 and an aspiration chamber 79 by a fluid impermeable barrier80 that completely segregates the two chambers 78, 79 within the device.The expansion and contraction of the irrigant chamber 78 causes fluidflow through a dedicated inflow line 2′ between the irrigation reservoir1 and the irrigant chamber 78 and out to the target exchange site viathe irrigation lumen 2 and terminates at the target site as in the otherembodiments described herein. Similarly, aspirant fluid is drawn inthrough the aspiration lumen 3 into the aspiration chamber 79 and outthrough the dedicated aspiration chamber outflow line 3′ and into theaspiration reservoir 4. As in the embodiment of FIG. 11, one-way flowvalves are advantageously disposed in each inflow and outflow linebetween the lumen and chamber, and chamber and reservoir. Thus, aone-way flow valve 81 a allows fluid flow only in the direction from theirrigation reservoir, via inflow line 2′, into the irrigation chamber78. The fluid inside the irrigation chamber 78 may only flow in thedirection through one-way valve 81 b and out through the irrigationlumen 2. Aspiration fluid entering aspiration chamber 79 via aspirationlumen 3 may enter only in the direction through one-way valve 81 c andaspiration fluid inside the aspiration chamber 79 may pass only in thedirection of the aspiration reservoir 4 through one-way valve 81 d.

[0084] Referring to FIG. 12B, pressure exerted on the compressiblestructure of the device, as indicated by the bold arrows in FIG. 12B,compresses both irrigant chamber 78 and aspirant chamber 79 such thatfluid flows in the direction of the arrows i.e. irrigant fluid flowsthrough one-way valve 81 b, through irrigation lumen 2 and to the targetexchange site. Aspirant fluid flows from the aspiration chamber 79through the one-way valve 81 d and into the aspiration reservoir 4.Fluid flow is prevented by one-way valves 81 c and 81 a from enteringeither the aspiration lumen 3 or the irrigation reservoir 1. Uponrelaxation, the outer surface of the handball moves in a directionopposite to the bold arrows in FIG. 12B and the flow is reversed. Thus,fluid flows from the irrigation reservoir 1 through the one-way valve 81a and into the irrigation chamber 78. Likewise, fluid flows from theaspiration lumen 3, through one-way valve 81 c, and into the aspirationchamber 79. This configuration is similar to the embodiment of FIG. 11because a chamber 78 or 79 is provided at an intermediate positionbetween the exchange site and the reservoir such that a volume of fluidis held at an intermediate position between each reservoir 78, 79 andthe exchange site for purposes of exerting control over a discretevolume of fluid separate from the irrigation and aspiration reservoirs1, 4.

[0085] However, the compressible handball configuration can beconstructed to allow direct manipulation of the irrigation reservoir 1to expel fluid while simultaneously collecting aspirant fluid within thediscrete structure of the handball itself. FIGS. 13A and 13B show ahandball pump configured with an internal reservoir of irrigant and aflexible barrier 82 to separate the irrigant and aspirant reservoirs 1,4, which are disposed inside the handball. Referring to the embodimentof FIG. 13A, prior to connection of this embodiment of the invention toa catheter element, the irrigant reservoir 1 is preferably filled withfluid to substantially encompass the entire internal volume of thehandball. The flexible and fluid impermeable barrier 82 deforms towardsthe outer wall of the handball to accept irrigant solution and tosimultaneously minimize the internal volume of the aspirant reservoir 4.When used in a clinical setting, the irrigant reservoir 1 is filled withthe pharmaceutically acceptable composition to be used as the irrigantand the apparatus is sealed and may be sterilized while intact. Beforeusing, the device is connected to the irrigation lumen 2 and aspirationlumen 3 which may be filled with fluid to establish the substantiallyclosed loop as described previously. As in the embodiment of FIG. 12Aand 12B, one-way valves 83 a, 83 b are positioned in-line between theirrigant reservoir 1 and the irrigation lumen 2, and between theaspiration lumen 3 and the aspirant reservoir 4. As the handball iscompressed, fluid flow generally occurs in the area of the arrows toforce fluid out of the irrigant reservoir 1, through the irrigationlumen 2 and into the target site while any backflow is prevented by theone-way valve 83 a. Accordingly, aspiration fluid is drawn through theaspiration lumen 3 and collects in the aspirant reservoir 4. FIG. 13Bshows an embodiment of the invention wherein approximately half of theirrigant solution has been expelled through the irrigation lumen 2,exchanged at the target site, and collected back in the aspirantreservoir 4 via aspiration lumen 3. As above, fluid flow generallyoccurs in the direction of the arrows as the internal irrigant volume isexchanged between the irrigant reservoir 1 and the aspirant reservoir 4.

[0086] As noted above, the principal of the invention may be achieved byboth user operated, generally mechanically controlled embodiments of theinvention, or through electronically controlled apparatus that usuallyrequire electronically controlled pumps and/or valves. In the embodimentof FIG. 13C, a volume metric pump 86 with an internal balloon 85 isprovided to achieve the fluid exchange function of the invention.Generally, the device is comprised of a housing 84 that is preferablysubstantially rigid and which contains an internal irrigant reservoir 1and aspirant reservoir 4 connected to dedicated irrigation andaspiration lumens 2, 3, as described previously. Volumetric control isachieved by selectively expanding an internal balloon 85 within thehousing 84 to be positioned in either the irrigant reservoir 1 oraspiration reservoir 4. As with the embodiments of FIG. 13A and 13B, ata preliminary point in the use of the device the irrigant reservoir 1 isgenerally full and the internal volume balloon 85 is confined in theaspirant reservoir such that the internal volume of the balloon 85 ismaximized within the aspiration reservoir4 and does not displace asubstantial volume of the irrigant reservoir 1. This allows the maximumamount of irrigation fluid to exist within the irrigant reservoir 1prior to use of the device. As the fluid exchange process occurs, thevolumetric pump 86 functions by forcing a portion of the internal volumeof the balloon 85 into the irrigant reservoir 1. The volumetric pump 86may be controlled by the user or through an electrical circuitry thatprovides an output reading to dictate the volumes or relative percentagevolumes between the reservoirs 1, 4. As the volume exchange processcontinues, the internal volume of the balloon 85 is transferred to agreater and greater degree from the aspirant reservoir 4 to the irrigantreservoir 1 to displace the internal volume of the irrigation fluid. Ata half-way point, the internal volume of the balloon is equally disposedbetween the two reservoirs (assuming that the beginning volume of thetwo reservoirs is equal) and the volumes of the fluid contained in boththe irrigant 1 and aspirant 4 reservoirs is equal. As describedpreviously, a simple modification of the dimensions of the apparatusallow variation of the volume exchange ratio from a 1:1 value to anyprescribed ratio dictated by the clinical circumstances.

[0087]FIG. 14 shows a side view of the device where the irrigation 90and aspiration 91 fluid impermeable chambers are contained in the same,preferably rigid housing 92 and are separated by a centrally disposedpiston 93 that engages the interior of the housing 92 about the entireperiphery thereof to segregate the irrigant fluid from the aspirantfluid and allows the piston 93 to slide within the housing 92. By movingthe piston 93 within the interior of the housing, typically from oneextreme end to another, the irrigant is forced out of the irrigantchamber 90 and into the irrigation lumen 2. Fluid exchanged at thetarget site is collected through the aspiration lumens and into theaspirant chamber 91. Thus, in the example of FIG. 14, when the piston 93slides from one end to the other, the irrigant chamber 90 expelsirrigant, while the aspirant chamber 91 simultaneously draws in aspirantfluid. Then, as the piston 93 is moved back in the other direction, theirrigant chamber 91 refills itself with fluid from the irrigantreservoir 1 while the aspirant chamber 91 expels its contents into theaspiration reservoir 4. As in other embodiments described herein, thissimple, compact arrangement allows for simultaneous irrigation andaspiration and yield a pulsatile flow. Although shown as a cylindricalhousing 92, the construction and arrangement of the input, output,reservoir and piston elements could be altered without departing fromthe spirit of the invention. In the embodiment of FIG. 14, the piston isdesigned to move repeatedly and reproducibly within the housing to expeland collect a defined volume of fluid with each operation cycle.

[0088] The volume of fluid exchanged at the target site with each cycleof the piston 93 is substantially equivalent to the internal volume ofthe housing 92 assuming that the piston 93 is moved from one extreme toanother extreme inside the housing 92 during each cycle of the operationof the device. This embodiment also demonstrates, as in the foregoingembodiments, that the fluid exchange device of the invention is readilyadapted to be controlled either manually, in this case through theapplication of force to a handle 94 attached to the piston 93, or byelectronic control, which in this embodiment would be provided by asimple pump or electrical or magnetic force to move the piston 91 withinthe housing 92. The separation of the irrigant and aspirant reservoirs1, 4 from an irrigant and aspirant chamber 90, 91 permits the device tobe repeatedly cycled to draw a defined volume into each chamber 90, 91for propulsion through the irrigation lumen 2 and collection through theaspiration lumen 3. In an alternate embodiment, the entirety of theirrigant fluid to be exchanged at the target site would begin containedwithin an aspirant reservoir that is entirely located within the housingsuch that movement of the piston 91 from one extreme of the housing 92to the other would communicate the entire volume of the irrigantreservoir 1 through the irrigation lumen 2, to the target exchange site,and back into the aspirant reservoir 4 via the aspiration lumen 3. Afurther example of this embodiment is shown in FIG. 15 below, having analternate mechanical expedient for propelling fluid from the irrigantreservoir 1 into an aspirant reservoir 4.

[0089] In the embodiment of FIG. 15, the irrigant and aspirantreservoirs 1,4 are separated by a fluid impermeable barrier 95 that ismovable about a threaded axis 97 or other structure that passes within aslidable member 96 that rotates and slides about the threaded axis 97 tomove the barrier 95 along the axis 97 to propel the irrigant fluid.Ideally, the slidable member 96 provide for a high rate of translation,while the member 97 provides for fine travel about the threaded axis 97.The sliding element can be selectively disengaged from the threads toallow it to slide rapidly along the threaded axis for gross adjustment.When engaged, the sliding element can be rotated for fine adjustment.Interior to the sliding element is a mechanism which permits thisselective thread engagement by retracting the thread contact whenactivated.

[0090] Referring to FIG. 15, this embodiment of the fluid exchangedevice is comprised of two main elements to achieve a configuration thatallows for the body or cylinder actuation of both syringes in thedesired and opposite manner. Essentially, a unitary body 101 connects ofone syringe element 102 a and is connected rigidly to the piston 103 bof the other syringe element. A slidable element 104 engages the unitarybody 101 and slides reproducibly in engagement therewith. As shown inFIG. 16, the slidable element 104 is also attached to the cylinder 103 aof one syringe and the piston 102 b of the other. Motion of the slidableelement 104 exerts a force withdrawing one piston while advancing theother and braces the application of force by the attachment of the body101 or element 104 to the cylinder or body of each syringe 102 a, 103 a.The design could incorporate existing syringes or have the syringeelements molded into the piece. There are several distinct advantages tothis embodiment. One is that it ensures a 1:1 exchange ratio in terms oftravel distance between the syringes. Another is that the geometricarrangement allows for a balancing of the forces involved in the device.Finally, the realization of the complex mechanics through just twomoving parts is a significant advantage for the manufacturing andefficiency of the device.

[0091] As described above, the element of turbulence is important to theefficacy of the device. Since fluids tend to assimilate to laminar flow,proximity of the irrigant ports or perforations that facilitatesturbulence is important for optimal rinsing of the interior of a bodystructure. For this reason, translation of the catheter element mayaccompany the irrigation or aspiration or both. All embodimentsdescribed herein can be manually translated by means of the operator'shand. Additionally, the catheter can be translated using an automatedtranslation system similar to those used in IVUS and similarapplications. Alternatively, the catheter could be translated by anelement incorporated into the fluid delivery device. Referring to FIG.17A a simple mechanism that could be used to realize this self-advancingaspect. When the catheter 7 element is moved to the left in thedirection of the arrows in FIG. 17A, the round engaging element 110slides up in the slot 111 and engages the catheter 7 to move it to theleft as well.

[0092]FIG. 17B shows the same mechanism. Once the catheter element 7 isslid to the right the round engaging element 110 slides down in the slot11 and allows the catheter element 7 to slide freely to the right in thedirection of the arrow without interacting or affecting the catheter'sposition. This allows for the selective retraction or advancement of thecatheter 7 by a predetermined amount with each squeeze of the device.There are many ways in which this element could be realized. Thesimplest would be an apparatus that selectively grasps the catheter whenmoving one direction and idles or does not grasp when moving in theopposite direction. A guiding track that biases the element could beused to apply pressure and grasp the catheter moving in one directionand then release and allow idle sliding to the reset position in theother direction. This element could be selectively engaged by theoperator when needed, and could be developed to allow for selectionbetween advancement and retraction of the catheter.

[0093] In the present preferred embodiment of the fluid exchange device,it is necessary to have a reset force supplied by an element such as aspring inherent in the device. This reset force is added to theresistance in the system that must be overcome by the operator toutilize the device. In some cases, an embodiment where this force wasminimized or eliminated would allow more of the force generated by theoperator to be directed to the work the device is performing and not toovercoming the reset force element. Referring to FIGS. 18A-18C, thisfunction could be achieved through the use of a staged device. FIG. 18Ashows a simple mechanical way in which the two sides of the device couldbe linked mechanically. It is important in this embodiment that the twosides be linked mechanically so that they behave in an equal andopposite manner. This is necessary so that the trigger can be actuatedrepeatedly in the same manner but engage just one of the sides whilestill driving the entire system. This allows the benefit of having theoperator not realize the changes occurring internally in the device. Thesqueezes would not feel substantially different. In this embodiment, thefirst squeeze would activate the two chambers and the second squeezewould reset the two chambers. A simple mechanical setup could achievethis result. Similar mechanisms are commonly used in objects such asretractable ball point pens. Essentially, an element attached to thetrigger element would be slightly biased to selectively engage one sideor the other of the device. FIG. 18B shows a top view of the tracklayout that would guide the selectively engaging element of the trigger.With the two sides linked mechanically to travel in equivalent andopposite manners as described elsewhere, the force of the triggerelement could always be applied in the same manner with varying effect.With the aid of the minimal return force element, the trigger is broughtback to its full and extended position and biased to one side so that itwill slip into the opposite track for the next actuation of the trigger.After that actuation, as the trigger is returning to its defaultposition, it will be biased to one side of the device and slip easilyinto the track of the opposite side.

[0094]FIG. 18C is a diagram of how the system could be achieved suchthat each time the trigger is expanded, it engages the other side of thedevice and pulls it back when squeezed.

[0095] Many features have been listed with particular configurations,options, and embodiments. Any one or more of the features described maybe added to or combined with any of the other embodiments or otherstandard devices to create alternate combinations and embodiments.Although the examples given include many specificities, they areintended as illustrative of only a few possible embodiments of theinvention. Other embodiments and modifications will, no doubt, occur tothose skilled in the art. Thus, the examples given should only beinterpreted as illustrations of some of the preferred embodiments of theinvention.

1. A system for irrigation and aspiration within a localized region ofthe body comprising: a fluid exchange apparatus comprising an irrigationreservoir and irrigation lumen having means for controlled delivery ofirrigant fluid from the irrigation reservoir through the irrigationlumen to a target site; an aspiration lumen having means for controlledcollection of aspirant fluid through an aspiration lumen; and a catheterelement comprised of the irrigation or aspiration lumen, wherein theirrigation lumen terminates with at least one irrigation port at adistal end of the catheter element and the aspiration lumen terminateswith at least one aspiration lumen such that fluid volume exchangeoccurs between the at least one irrigation port and the at least oneaspiration port.
 2. The system of claim 1 wherein the means forcontrolled delivery of irrigant fluid is comprised of a cylinder with adedicated piston for forcing fluid from the cylinder.
 3. The system ofclaim 1 wherein the means for controlled collection of aspirant fluidfrom the target site is comprised of a cylinder with a dedicated pistonfor drawing fluid into the cylinder.
 4. The system of claim 2 whereinthe piston and cylinder are components of a replaceable syringe.
 5. Thesystem of claim 1 wherein the fluid volume exchange creates turbuelence.6. The system of claim 1 further comprising an occluding elementproximal of the at least one irrigation and the at least one aspirationport.
 7. The system of claim 6 wherein the occluding element is aballoon.
 8. The system of claim 1 wherein the fluid exchange apparatusis further comprised of an irrigation chamber having an inflow line influid communication with the irrigation reservoir and wherein theoutflow line is in fluid communication with the irrigation lumen.
 9. Thesystem of claim 1 wherein the fluid exchange apparatus is furthercomprised of an aspiration chamber having an inflow line in fluidcommunication with the aspiration lumen and an outflow line in fluidcommunication with the aspiration reservoir.
 10. The system of claim 1wherein the fluid exchange apparatus is comprised of a trigger andhandle adapted to be held by the hand and which are activated to deliverirrigant fluid to the target site.
 11. The system of claim 1 wherein thefluid exchange device is comprised of an electronically controlled pump.12. The system of claim 1 wherein the means for controlled collection ofaspirant fluid is comprised of at least one one-way valve in fluidcommunication with the aspiration lumen.
 13. The system of claim 1wherein the means for controlled delivery of irrigant fluid is coupledto the means for controlled collection of aspirant fluid to produce apredetermined ratio of fluid volume exchange at the target site.
 14. Thesystem of claim 13 wherein the ratio is approximately 1:1.
 15. Thesystem of claim 13 wherein a ratio of irrigant to aspirant volume isbetween approximately 1:2 and 2:1.
 16. A fluid exchange device for fixedvolume fluid exchange within a body lumen comprising: means forproducing a pulsatile flow within the body lumen comprising: means forcontrolled delivery of a fixed volume of irrigant fluid from anirrigation reservoir through an irrigation lumen and an irrigation portlocated at the distal end of a catheter; means for controlled collectionof a fixed volume of aspirant fluid from an aspiration port located inthe distal end of the catheter through an aspiration lumen and intoaspiration reservoir, wherein the means for controlled delivery andmeans for controlled collection are linked and produce the fixed volumeexchange of the irrigant fluid and the aspirant fluid by the pulsatileflow at a target fluid exchange site within the body lumen.
 17. Thedevice of claim 16 wherein the means for controlled delivery of a fixedvolume of irrigant fluid is comprised of a member connected to a pistonthat propels irrigant fluid and that is linked to a second memberconnected to a piston that withdraws aspirant fluid.
 18. The device ofclaim 17 wherein the means for controlled collection of a fixed volumeaspirant fluid is comprised of a member connected to a piston thatwithdraws aspirant fluid and that is linked to the piston that propelsirrigant fluid.
 19. The device of claim 17 wherein the second member isconnected to the body of a cylinder containing the piston that propelsirrigant fluid.
 20. The device of claim 16 wherein the means forcontrolled delivery of a fixed volume of irrigant fluid is a syringe influid communication with the irrigation lumen, and wherein the syringeis linked to the means for controlled collection of a fixed volume ofaspirant fluid.
 21. The device of claim 16 wherein the means forcontrolled collection of aspirant fluid is comprised of a syringe influid communication with the aspiration lumen, and wherein the syringeis linked to the means for controlled delivery of a fixed volume ofirrigant fluid .
 22. The device of claim 20 further comprisingirrigation and aspiration lumens connected to the handball with one-wayvalves.
 23. The device of claim 20 wherein the means for controllingdelivery of irrigant fluid is comprised of an irrigation chamber andaspiration chamber each having inflow and outflow lines each havingone-way valves.
 24. The device of claim 20 wherein the means forcontrolling delivery of the irrigant fluid is a unitary housingsegregated into irrigant and aspirant reservoirs and having a singlepiston disposed between the irrigant and aspirant reservoirs.
 25. Thedevice of claim 16 wherein the device comprises a trigger actuated toproduce a predetermined volume of fluid exchange upon a single actuationof the trigger.
 26. The device of claim 25 wherein the trigger isconnected to a piston and actuation of the trigger applies force to thepiston.
 27. The device of claim 25 wherein the trigger is configured tobe cyclically actuated to produce repeated and incremental fixed fluidexchanges through incremental movement of the piston.